It means a fly ash which is reprocessed in compliance to Korean Quality
Standard (KS L 5405) regulates a quality of fly ash for use in concrete.

ITEM Regulations
SiO2 45% Min
Moisture 1% Max
Loss of Ignition 5% Max
Specific Gravity 1.95 Max
Surface Area of Fineness
(Brain method) /g
2400 Min
Compressive Strength % 28 day 60 Min

Size : Generally 1 ~ 100 and 20 ~ 30 in average
Shape : Sphere
Color : Gray

It consists chiefly of 50 ~ 60% of SiO2, 20 ~ 25% of Al2O3 and other
trace elements such as C2O, MgO, Na2O, K2O

Most of refined fly ash are used in conrete / remicon as substitute for
Portland cement. Even though not fixed but it could be replaced in propotion
fo 5 ~ 20% for Portland cement, which consequently improve the quality of
concrete and cost-savings.